Solution:

In order to minimize the time for the ant to crawl from point A to point B, it should take as few changes of direction and crawl vertically as few times as possible. The ant can crawl 2 units upwards from point A, change direction to right, then crawl 5 units horizontally, then change to upwards direction, finally crawling 1 unit and reach the point B. So the minimum time requires 2 x 6 + 1 + 5 x 5 + 1 + 6 = 45 seconds